A two-alarm fire broke out in a four-story residential building on Leavenworth Street in Russian Hill Wednesday afternoon, and one person has been seriously injured.

The SF Fire Department tweeted that the fire began at 1625 Leavenworth around 1:40 p.m., and as of 2:38 p.m. the blaze was contained. The cause of the fire is under investigation.

One person was reportedly taken to the hospital with serious burns, and was in critical condition.

The SFFD Public Information Officer, Captain Jonathan Baxter, reported that three units were most affected on the third floor of the building, however video from the scene appeared to show smoke and fire damage on the top or fourth floor as well.

Reportedly, 20 individuals were displaced in this fire, and the Red Cross was on the scene offering assistance.